Wednesday 14 January 2015 – Afternoon - · PDF fileWednesday 14 January 2015 – Afternoon LEVEL 1/2 CAMBRIDGE NATIONAL IN SYSTEMS CONTROL IN ENGINEERING R113/01

Wednesday 14 January 2015 – AfternoonLEVEL 1/2 CAMBRIDGE NATIONAL IN SYSTEMS CONTROL IN ENGINEERING

R113/01 Electronic principles

INSTRUCTIONS TO CANDIDATES

• Use black ink. HB pencil may be used for graphs and diagrams only.• Complete the boxes above with your name, centre number and candidate number.• Answer all the questions.• Write your answer to each question in the space provided. Additional paper may be

used if necessary but you must clearly show your candidate number, centre number and question number(s).

• Do not write in the bar codes.

INFORMATION FOR CANDIDATES

• The total number of marks for this paper is 60.• The number of marks for each question is given in brackets [ ] at the end of the question

or part question.• Dimensions are in millimetres unless stated otherwise.• Your quality of written communication will be assessed in questions marked with an

asterisk(*).• This document consists of 16 pages. Any blank pages are indicated.

* R 1 1 3 0 1 *

OCR is an exempt CharityTurn over

© OCR 2015 [A/505/3542]DC (NH/AR) 105116/1

Candidates answer on the Question Paper.

OCR supplied materials:None

Other materials required:• A calculator may be used

*4998359328*

Duration: 1 hour

Oxford Cambridge and RSA

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Answer all questions.

1 (a) Complete the table by naming each component from its symbol shown.

[5]

(b) A potential difference of 2 volts is applied across the terminals of a 10 ohm resistor.

Calculate:

(i) The current flowing through the resistor.

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(ii) The power absorbed by the resistor.

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(c) Fig. 1 shows a fixed resistor and a resistor colour code chart.

Digit 1 Digit 2 Multiplier Tolerance

black 0 black 0 black 0 brown 0.01

brown 1 brown 1 brown 1 red 0.02

red 2 red 2 red 2 gold 0.05

orange 3 orange 3 orange 3

yellow 4 yellow 4 yellow 4

green 5 green 5 green 5

blue 6 blue 6 blue 6

violet 7 violet 7 gold 0.1

grey 8 grey 8 silver 0.01

white 9 white 9

Fig. 1

Use the resistor colour code chart to determine the value of the fixed resistor shown.

Resistor value = ............................................. Ω[1]

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2 (a) Fig. 2 shows a circuit diagram.

touch across these contacts

+9V

0V

100 k

470

Fig. 2

(i) Name the type of transistor that is being used in the circuit.

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(ii) Give the name that is used for the combination of the two transistors shown.

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(iii) What type of switch could be used instead of the ‘touch across these contacts’ layout?

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(iv) Explain the purpose of the 470 Ω resistor used in this circuit.

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(v) Explain why a 100 kΩ potentiometer is used rather than a fixed resistor.

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(b) Explain what happens to the Light Emitting Diode (LED) when the touch contacts are closed.

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Turn over for next question.

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3 (a) The list below shows four different capacitor values.

2.2 μF 2.2 nF 2.2 pF 2.2 F

(i) State the lowest capacitance value in the list.

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(ii) State the highest capacitance value in the list.

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(b) State the precaution that needs to be taken when placing an electrolytic capacitor in a circuit.

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(c) Draw a labelled circuit diagram that could be used for charging and discharging a capacitor using a d.c. supply.

[3]

(d) Explain what is meant by the term ‘time constant’ in an RC circuit.

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(e) A 47 μF capacitor is connected in series with a 100 kΩ resistor to a 500 V d.c. supply.

Calculate the time constant of the circuit.

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Turn over for next question.

PLEASE DO NOT WRITE ON THIS PAGE

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4 (a) Fig. 3 shows a mains powered soldering iron.

Fig. 3

Describe how a component can be connected in a circuit using a hand soldering method.

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(b)* Discuss the implications for a manufacturer when considering the method of quality assurance used during commercial printed circuit board (PCB) production.

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5 (a) Fig. 4 shows a virtual oscilloscope being used as a test instrument in a simulated situation.

9630

voltage (V)

time (ms)

graph of oscilloscope output

function generator oscilloscope

Ch.1 Ch.2

0 10 20 30 40 50 60 70 80 90 100

Fig. 4

(i) Name the waveform shown on the graph of the oscilloscope output.

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(ii) Describe what happens to the shape of the output waveform if the X control on the oscilloscope is increased or decreased.

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(iii) Describe what happens to the shape of the output waveform if the Y control on the oscilloscope is increased or decreased.

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(b) One method of finding a fault in an electronic circuit is by using test equipment.

(i) Other than an oscilloscope, name three items of test equipment that are used to find a fault in an electronic circuit.

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(ii) Explain what is meant by the ‘half split’ method to find a break in the circuit.

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6 (a) Fig. 5 is a block diagram of a control system.

Fig. 5

State which block represents:

(i) feedback

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(ii) input

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(iii) output

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(b) The diagram is made up of four blocks.

(i) Explain the function of the process block.

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(ii) State whether the system is open loop or closed loop control.

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(iii) Give a reason for your answer.

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(c) State three practical applications that use a closed loop control system.

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END OF QUESTION PAPER

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Wednesday 14 January 2015 – Afternoon - · PDF fileWednesday 14 January 2015 – Afternoon LEVEL 1/2 CAMBRIDGE NATIONAL IN SYSTEMS CONTROL IN ENGINEERING R113/01